[sdiy] lin to log envelope

[gregory zifcak]

thanks,

they don't have vc inputs, but they're simple decay envelopes based around 
an opamp, a couple resistors, a capacitor and a couple of diodes. the 
schematic shows the output of the opamp feeding back to the inverting input. 
i am wondering if its simply a matter of rerouting this to the positive 
input of the opamp (possible through a pot to allow continuously variable 
decay shapes?).


>From: Peter Grenader <peter at buzzclick-music.com>
>To: gregory zifcak <zifcak at hotmail.com>, <synth-diy at dropmix.xs4all.nl>
>Subject: Re: [sdiy] lin to log envelope
>Date: Tue, 18 Nov 2003 16:49:05 -0800
>
>If your envelope phases are VC'able, its cakewalk - output of envelope into
>VC input.  If it's not, then well...you're going to have to do some cutting
>and hacking to get it in there.
>
>
>
>
>
>
>
>gregory zifcak wrote:
>
> > hello,
> >
> > i saw in the archives a reference to changing the shape of envelopes by
> > feeding them back into themselves either positively or negatively. does 
>this
> > refer to the positive and negative inputs of the opamp?
> >
> > my application is this:
> > i have a simmons sds800 which uses cem3394 chips for osc-vcf-vca. 
>according
> > to the datasheet, the vcas are approximately exponential, allowing
> > exponential volume shapes with a linear envelope. i am assuming that the
> > simmons envelopes are linear or maybe even exponential, because they are 
>not
> > particularly punchy. i would like to make them logarithmic if possible 
>in
> > order to obtain punchy, linear dynamic response.
> >
> > so basically my question comes down to where do i feed(back) the output 
>of
> > the envelope?
> >
> > thanks for any info,
> >
> > greg
> >
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>

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